3.6.2, 6.6.5, 7.2, 3.6.6
Pipe in Concrete Need not Corrode. A. W. Peabody. Ebasco Services, Inc. Consulting Engr., 12, No. 3, 104-107 (1959) March.
Usual cause of rapid corrosion of steel radiant heating piping installed under concrete is use of a type of construction that creates conditions favorable to formation of strong galvanic corrosion cells (concentration cells) at pipe surface. When pipes are laid directly on a base layer of sand, earth, vermiculite, or other similar material and then covered with poured concrete, small portions of pipe surface are in contact with soil or vermiculite base layer. Voltage between concrete and steel is sufficiently different from that between soil and steel to set up a flow of corrosive current, direction of which is such that steel contacting soil is corroded. Prime requirement for a suitable design is that liquid-carrying steel heating pipes be totally enclosed in concrete slab....
